Method of treating a fabric formed from cellulose fibres to render said fabric drip-dry



United States Patent This invention relates to a method of treating fabrics formed from natural or artificial cellulose fibres, to render them drip-dry.

Various processes are already known for producing cellulose fabrics whose particular property is that they uncrease when immersed in water or any aqueous solution. The practical advantage of such fabrics is that they do not have to be ironed, since they can be taken out of water of the like and drip dried.

The known processes are generally based on the reaction of halohydrin on cellulose. This long known reaction has been used in various processes for giving fabrics specific properties such as elasticity, making them shrink-proof, and so on. Ithas also been used in processes for making fabrics drip-dry, as in the Belfast process forming the subject of Belgian Patent No. 556,- 279. This process is based on the reaction of u-dichlorohydrin, fl-dichlorohydrin, or epichlorohyd-rin on alkali cellulose. It comprises impregnating a fabric successively with a solution of an alkaline hydroxide and a solution of the reagent used (dichlorohydrin or epichlorohydrin). Two different baths must therefore be use successively, and this of course is a disadvantage of this process. It is due to the fact that it is very difiicult to produce a single stable bath because of the rapid hydrolysis of chlorohydrin in the presence of concentrated alkali.

The other disadvantage of this process is that it is impossible to control the reaction between halohydrin and cellulose, and this leads to waste of the halohydrin derivative used. Finally, the results obtained are not satisfactory.

The method according to the invention eliminates the above disadvantages of the known processes. It is characterized in that the fabric is impregnated with an aqueous suspension containing at least one alkaline hydroxide and at least one halohydrin ester of one of the following two formulae:

R being an organic or inorganic "acyl radical and X a halogen, and in that the stability of the emulsion is maintained for the time required for the reaction, at the end of which the fabric is rinsed and dried.

-It will 'be seen that the method according to the invention comprises the use of a halohydrin ester instead of the :halohydrins themselves, thus enabling the reaction with cellulose to be carried out in a single bath containing the said ester in suspension in an aqueous solution of an alkaline hydroxide. Such esters are sufficiently stable at ordinary temperatures in the presence of even concentrated alkaline hydroxides, so that stable emulsions or suspensions of these esters can be prepared in aqueous solutions of alkaline hydroxides, e.g. of sodium or potassium. The reaction time is approximately 24 hours. This time can of course be reduced 'by heating the fabric after impregnation.

Such heating of the impregnated fabric enables the ester to liberate the halohydrin by hydrolysis, the halohydrin reacting with the cellulose in highly alkaline conditions of the emulsion or suspension with which the fabric is impregnated. The reaction time therefore depends on the temperature at which the reaction is carried out. This temperature may be between 0 and 200 C., but is preferably from 10 to 40 C.

To avoid evaporation of the liquid contained in the fabric, the later may be treated while being reeled and enclosed in a chamber or an autoclave or a similar system preventing evaporation, even above C.

The organic or inorganic acyl radical may, for example, be 'acetyl, 'benzoyl, phosphoryl, or the like. The halohydrin may be a chlorohydrin, bromohydrin, and the like. The alkaline hydroxide may be sodium, potassium or lithium hydroxide.

To increase the stability of the emulsion or suspension still further, an emulsifying surface-active agent may be added. For the same purpose of stabilising the emulsion or suspension, an agent may be added to thicken one of the two phases, preferably the aqueous phase. This thickening agent may, for example, be a soluble derivative of cellulose, or of polyvinyl alcohol.

Finally, the emulsion or suspension may be stabilised by the addition of inhert agents in one or other of the two phase so as to make their densities equal and improve the penetration of the emulsion constituents throughout the fabrics for treatment.

In the particular case in which halohydrin acetate is used, at least one light hydrocarbon, such as hexane, may be successfully used as an inert agent so that the organic phase has a density equal to that of the aqueous phase initially. In addition, as the treatment progresses, the densities of the two phases can be kept as close as possible by controlling the evaporation of the hydrocarbon.

The method according to the invention has the following advantages:

A single bath can 'be used, thus facilitating operation.

The halohydrin can be liberated progressively, thus promoting the reaction between the halohydrin and the cellulose to the deteriment of hydrolysis of the latter, thus effecting a saving of the halohydrin derivative.

The non-creasing effect of the fabric is improved.

The swelling of the fabric is improved, thus enabling finer 'basic fabrics to be used.

The softness is improved, thus enhancing the feel of the fabric when worn.

The method according to the invention may be carried out, for instance, according to the following examples:

After 100% pick-up squeezing, the fabric is kept in a closed chamber at a temperature of 20 C. for 24 hours. The cotton fabric is then washed and neutralised.

This treatment gives the fabric permanent drip-dry properties. The mechanical strength loss of the fabric is negligible.

Example 2 Parts by weight 24% aqueous KOH solution 20 1,2-dichloroprop-anol-3 acetate 6 n-Butanol 0.5

3 The impregnated fabric squeezed with an 80% pickup is heated to 100 C. for 30 minutes in a saturated vapour atmosphere.

After washing and neutralisation, the drip-dry properties are similar to those in Example 1.

Example 3 Aqueous solution: Parts by weight Methyl cellulose 5 Sodium hydroxide 60 Water 985 Sodium sulphide -78 Organic solution:

Emulsifier 5 Dichlorohydrin propionate 80 where R is a radical selected from the group consisting of organic and inorganic acyl radicals and X is a halogen, maintaining the stability of the emulsion for a suflicient period for the halohydrin liberated by said emulsion to react with said fabric, rinsing said fabric, and then drying said fabric.

2. The method set forth in claim 1 further including the step of heating said fabric to a temperature not exceed ing 200 C. to accelerate reaction of said liberated halohydri-n with said fabric.

3. The method set forth in claim 2 wherein said fabric is reeled and said method is carried out in an autoclave to minimise evaporation of liquid from said fabric.

4. The method set forth in claim 1 wherein said alkaline hydroxide is selected from the group consisting of sodium hydroxide, potassium hydroxide and lithium hydroxide.

5. The method set forth in claim 1 wherein said radical R is selected from the group consisting of acetyl, benzoyl and phosphoryl.

6. The method set forth in claim 1 wherein said halogen is selected from chlorine and bromine.

7. The method set forth in claim 1 wherein said aqueous emulsion further includes an emulsifying agent.

8. The method set forth in claim 1 wherein said aqueous emulsion further includes a thickening agent.

9. The method set forth in claim 8 wherein said thickening agent as a soluble derivative of cellulose.

10. The method set forth in claim 1 wherein said aqueous emulsion further includes a light hydrocarbon as an inert stabilising agent.

11. The method set forth in claim 10 wherein said light hydrocarbon is hexane.

No references cited.

NORMAN G. TORCHIN, Primary Examiner.

T. J. HERBERT, Assistant Examiner. 

1. A METHOD OF TREATING A FABRIC FORMED FROM CELLULOSE FIBERS TO RENDER SAID FABRIC DRIP-DRY, WHICH COMPRISES IMPREGNATING SAID FABRIC WITH AN AQUEOUS EMULSION CONTAINING AT LEAST ONE ALKALINE HYDROXIDE AND AT LEAST ONE HALOHYDRIN ESTER OF ONE OF THE TWO FOLLOWING FORMULAE: 